Method of constructing thermopiles



March 16, 1954 SUKACEV METHOD OF CONSTRUCTING THERMOPILES Original Filed March 9, l

rib?! Patented Mar. 16, 1954 2,671,950 ME'rnon F ooNs'rnUoTi G Tnnnmorrcss ilevsukaeevg'ChevyChase, M di Original edit-sta nant '9, i950," serial No.

148,660,. -,Div.ided and this. application March ?a m te- 11 metallic ribbon .having" the configuration of a;

helix and having sections ofionemetalalternating with sections of another metalconnected in series in overlapping relationship; .The metals i are properly separated from each other irf'theelectromotive force series of elements .tololotain a thermoelectric action; .Each section is of'such length that alternate junctions between the metals are groupedon'honesid'e"of the. helix3and intermediate, junctions aregrouped on substantially'the' opposite side'of the helix; i Relati'vely simple and inexpensive methods are employed inconstructing this thermopile. .Acore of any desirable 'for'msuch as a rodgandicompristing dielectric material, iscoated onionesi'd'e with alayer of one of thefmetals 'of the thermopile, and the other side 'of the core is coated witha layer at the other metal of the thermopile. These layers are so applied that the longitudinal edges thereof are in overlapping".cont'act with each other. Acuttingl'insti-ument is then applied to the" coated core and alcut is made through" the coatings into the core in the form of a helix, ex tending from one end of the core to the other. Thus, it isseen that a thermopile is formed having th hereinedescribed structure.

The inventionis described hereinbelow in further detail, by Way of example, with reference to the accompanying dravv'ing; '-in which Fig. 1 is a sideview ofathermopile according to the invention; Fig- 2 is an enlarged sectional view on line 2-2 of Fig, 1;; a l an": 1 Pipe 2 1 'Flgm 3 is an enlarged vertical section taken ngitudinall y of a fragment of the thermopile shown il'li Eig-ilfi- J H 4. :1 us :1,

i Flgswl, 5 and 6 are diagrammatic views showing respectively a vertical longi-tudinal sectiong .a vertical lateral section, and a plan View of apparatus to illustrate stepsin amethodof making the thermopile. constructing a thermopile of the present invention, a rod of dielectric material I of any desired length and. cross-section is provided with a thin conductor coating 2 of relatively high electrical resistance as compared with the metals employed in the thermopile. By employing the thus coated rod as an electrode, one side is electroplated with one of the metals 3, such as copper, to serve in the thermopile. The opposite side is electroplated with a different metal 4, such as nickel. The edges of the metal layers 3 and 4 overlap as at 5 and 6 on substantially diametrically opposite sides of the rod I.

After the metal layers 3 and 4 are provided, the coated rod is revolved on its longitudinal axis while a continuous cut 1 is made through the applied *layers and partly into the dielectric ma aterial of "the rod: I: fThe cut 'Iis substantially-in a" helical-dine extendine' from one end- 8- 'to the; other end 9* of the 'rod-I'.- A helical strip or-rib' 1 hon is' thereby *formedwith a section 3 of==-coppe1= andJa sec'tionl of nickelin each turm each endoteach section firmly contacting and overlapping the end of the next adjacent section, thereby forming the thermocouples otthe-pile. Edges between the turnsrin the-ribbon are maintained separated by aspaceequal to the widthof the cut 1;;A terminal maybe provide'd-at each end of the helical-thermopile as'atland I la:

The red- @I shown, is circular in cross-section though this -mayhe rectangular, elliptical-l or thermoplastic 'or thermosetting"depending onthe conditions under which,the--thermopile-is 9 be employed. "J 1'? In making a thermopile by an electroplating process, for example,- a: rod I4 ofrdielectrie material is providedjwith means wherebywit' may serve asa" cathode. .f'FQI "thispurpose. a pair" 01f angular metal supporting means is screwed" into thefside 'Of'TOdEIMI lJ each end as at I 5, I I and I8. The "metal supportingmeans in eachfiend extend "in opposite directions-from the; side of therod. ,The rod with these attachments is then provided with a conductorcoating of :relatively high resistance, namely, in the-following manner"; The rod-is-cleaned-with a1cohol5and; submerged in "a"5 per cent solution of tin' chloride for ;1;5 minutes. The 'rod isremoved and washed, an coated with a film 'ofsilver-of suchthinnessthat its resistance -is'-relatively high.- This is done by placing "the. rod in? a bath preparedfrom 20 parts I. ofya solution A and. 1 part of, a solution Bul he formula; "of each solutionbeing thatjindigat ed b l l e a... w,

The rod is removed from the silvering bath after about minutes and is washed and dried. It is now ready for electroplating. It is noted that the silver film covers the entire surface of the rod and makes electrical contact with the metal supporting means l5, l6, l1 and I8.

Instead of silver, it is possible to attach a thin continuous layer of carbon particles to the surface of the rod, and then to subject the coated rod to the electroplating process described below.

For purposes of exemplification, the electroplating apparatus shown in Figs. 3, 4 and 5, comprises a tank containing electrolyte 2|. 22 represents an anode of the metal to be deposited on the rod Hi. The anode 22 is electrically connected to and suspended from conductors 23 and 24. The silvered rod ll, serving as a cathode, is suspended in the electrolyte by means of conductor elements 25 and 26 upon which the ends of the metal supporting means l5 and I1 rest. Proper connections are made to complete an electric circuit through the electrolyte.

To coat one side of the rod I I with copper, for instance, the rod is positioned in a copper bath, as shown in Fig. 3, and the level of the bath is maintained so that the rod is submerged to a depth slightly greater than its radius. After the copper is deposited to a thickness substantially greater than the thickness of the silver film, the rod is removed from the copper bath, washed, dried, and the other side of the rod is coated with nickel, for instance, by placing it in a nickel bath and supporting it by the means I6 and la in a manner similar to that in which it is supported in the copper bath. As in the case of the copper bath, the level of the nickel bath is maintained so that the rod is submerged to a slightly greater depth than its radius to insure overlapping of the deposited meta1 layers, as shown in Figs. 1 and 2.

After the copper and nickel layers are deposited on the rod M, in the manner described, one of the metal supporting means I B and I! at either end is removed and the angle end of the metal supporting means l5 and I8 is cut oi! to form the terminals similar to the terminals [0 and I l in Fig. 1. By the electroplating process described, good electrical contact is made between the deposited metal layers and these terminals.

Electroplating is preferred, but an alternative method of applying the metals of the thermopile to a core, comprises shielding substantially one longitudinal half of the core while exposing the other half to a metal vapor to obtain a coating, then shielding the resulting metal coating with the exception of a strip along each edge of said coating, and exposing the remainder of the surface to vapor of a different metal until a coating of the latter metal is formed which overlaps the said first metal in said strips.

The helical cut is next made in the side of the rod through the coatings and into the dielectric material underneath. A ribbon of any desired width may thus be obtained with terminals at either end. The thermocouples in the pile are in alignment on opposite sides of the helix. The dielectric material serves to mount the metals of the pile on a solid base of any desired length usable as a thermopile unit and for easy installation. A simple, efiicient pile is readily constructed and adapted to various uses. Its electromotive force may be easily varied with the length of the helix, by the number of turns in the helical ribbon, by the metals used, by coupling any number of these piles, and by other means.

The invention as hereinabove set forth is embodied in particular forms and manner but may be variously embodied within the scope of the claim hereinafter made.

This is a division of application Serial No. 148,660 filed March 9, 1950. l

I claim:

A method of making a thermopile, which method consists of the following succession of steps in the order stated: coating with one metal substantially one longitudinal half of a rod-like core of uniform cross section and consisting of a dielectric plastic material, coating the remaining portion of the core and a strip along each edge of the said one metal with a different metal for forming thermoelectric connections on the surface of said core, and cutting a kerf through the resulting coatings and into the rod-like plastic core on a line extending continuously around the core in the form of a helix, to provide a rod-like product consisting of a helix of metal in ribbon form with sections of said one metal alternating with sections of said different metal in series in overlapping relationship and attached to the surface of the solid plastic core in raised position with respect to the material of the said core.

LEV SUKACEV.

References Cited in the file of this patent I UNITED STATES PATENTS Number Name Date 1,441,569 Fischer Jan. 9, 1923 1,748,822 Arsem Feb. 25, 1930 1,767,715 Stoekle June 24, 1930 1,809,089 Wiegand June 9, 1931 1,994,767 Heintz Nov. 19, 1935 2,557,571 Siegel June 19, 1951 FOREIGN PATENTS Number Country Date 24,968 Great Britain of 1899 

